DIFFERENTIAL DIAGNOSIS

Duffy (1995) suggests that the etiology can be neurogenic, psychogenic, and idiopathic, while Higgins, Chait, and Schulte (1999) argue this by stating "Although there has been some reference to psychogenic cases of AdSD that do respond to voice therapy, Sapir (1995) has argued that such disorders must be clearly distinguished as nonorganic entities that merely share some of the symptoms of AdSD." Other similar disorders are musculoskeletal tension dysphonia and psychogenic dysphonia.

SD is as common in women as it is in men. In the past few years there has been an increase in the number of identified cases of SD. There are some reports of a relation of SD to a familial history of the disorder.

The diagnosis of SD is very difficult. In most cases, SD is not identified usually until a year post onset. It can be triggered by a number of incidences such as a cold or flu, and is sometimes associated with a life event or trauma, while others reported that their voice disorder began with mild symptoms and developed into spasmodic dysphonia. Here are some differentiating characteristics of SD along with some similar voice disorders.

Case History

MTD (Musculoskeletal Tension Dystonia)	generally reports stressful events during the onset of symptoms
PD (Psychogenic Dystonia)	generally reveals a traumatic life event or stress
SD (Spasmodic Dysphonia)	generally reports an increase in stress since the onset of symptoms

MTD	voice symptoms are consistent and are not influenced by phonemic context somewhat predictable episodes of vocal tension tension visible during direct examination persons respond well to voice therapy
PD	voice problems may vary but show variability within phonemic contexts unique voice characteristics present with no developing patterns possible reports of the voice returning for hours, days, weeks, or months at a time symptoms are not present during reflexive phonation acts respond well to voice therapy
SD	voice has limited variability with consistencies in various phonemic contexts return of normal voice characteristics as with PD symptoms reflect the nature of the underlying etiology (spastic) do not respond well to therapy